1. Field of the Invention
The invention relates to the attachment of a braking device, in particular a drum brake, to a frame part of a bicycle.
2. Description of the Related Art
The attachment of a prior art drum brake to the frame part of a bicycle is usually performed after the drum brake has been assembled with a hub of a bicycle wheel via an axle of the hub connected on the frame part of the bicycle. An extension arm connected to the brake for dissipating brake reaction forces is likewise fastened on the frame part after the extension arm has been brought into the correct position in relation to the frame part. One example of a prior art drum brake with an extension arm is described in German patent application DE 195 36 157.1 A1. In this reference, the extension arm has a support which is fastened on the frame part of the bicycle by a bolted joint or has a bracket or the like, which can be joined to the frame part. It is always the aim of such a construction to create an extension arm which is suitable for attachment to all different types of frame parts (i.e., universal attachment) and, moreover, can as far as possible also be attached to both running wheels of the bicycle.
The subject matter of the present invention relates to a specific attachment of a braking device on a bicycle frame part which is specifically designed for a disk type of braking device. That is, the present invention concerns the segment of bicycles where a disk brake is mounted on both running wheels, or at least on the front wheel. In contrast, the prior art focusses on the design of a universal attachment for the extension arm of braking devices.
Equipping this type of bicycle with drum brakes as it is initially fitted out, or at least by retrofitting, is the object of the present invention. The present invention dispenses with the technically demanding mounting step of positioning the extension arm with respect to the frame part before the axle of the hub is fastened in the drop-out ends of the bicycle.
In general, the manufacturers of bicycles with disk brakes now use a configuration for dissipating the reaction force produced during braking to a fastening element which is arranged on the frame part in the vicinity of one of the drop-out ends of the bicycle frame. The fastening element is a metal plate with two bores, at which there can be fastened a caliper which has brake blocks which are pressed against a brake disk bolted to the running wheel. During the braking of the brake disk and consequently of the running wheel, the brake reaction force is transmitted from the brake blocks via the caliper to the fastening element and consequently to the frame part.
According to the invention, to retrofit a drum brake on a bicycle designed for disk brakes, an adaptor is attached at one of the bores of the fastening element. The adaptor is preferably a simple-to-produce rotationally symmetrical part and has a groove in which a recess of an extension arm on the drum brake can engage.
According to the present invention, a braking device which comprises a brake carrier with brake shoes and an extension arm is brought together with a hub to form a structural unit. The hub has an axle and the structural unit allows itself to be fastened on the fastening part of the bicycle both by the axle being pushed into drop-out ends on the frame part of the bicycle and by the extension arm simultaneously being pushed into the adaptor. The mounting and removal of the running wheel are consequently reduced to the pushing-in described above and, in addition, tightening of axle nuts on the axle. No additional fastening operations at the joint connecting the extension arm to the adaptor are required. The recess on the extension arm is preferably designed such that it tapers in a funnel-shaped manner to make the joint between the extension arm and the adaptor virtually free from play. Needless to say that, as on all brakes, a remote control for actuating the braking device must be fitted here.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.